1. Field of the Invention
This invention relates to an improved control device, such as for controlling the operation of an exhaust gas recirculation valve for an internal combustion engine of a transportation vehicle or the like.
2. Prior Art Statement
It is known to provide a self-contained control device for an exhaust gas recirculation system for an internal combustion engine having a first source provided with a changeable fluid pressure value and a second source provided with a changeable vacuum value and having a pressure operated control unit that changes its operating condition in relation to the value of the pressure signal directed thereto and controls the amoung of exhaust gas recirculation. The self-contained control device has pneumatically operated control means adapted to be operatively interconnected to the sources and to the control unit for increasing the pressure signal from the first source to the unit as the pressure value from the first source increases from a first value thereof to a second value thereof and for thereafter decreasing the pressure signal from the first source to the unit as the pressure value from the first source further increases from the second value thereof to a third value thereof, the control means being adapted to produce the signal in substantially the same manner but at different values for different levels of vacuum at the second source thereof. The control device comprises at least three housing plates disposed in stacked relation and the control means comprise a plurality of pneumatically operated relay means defined in part by the housing plates and each having diaphragm means disposed between certain of of the housing plates.
For example, see the following patent application: (1) Ser. No. 800,211 filed May 25, 1977 and now issued as U.S. Pat. No. 4,099,539.